Manhole construction.



No. 835,012. QPATENTED NOV. 6, 19 06.

- 1). CRAIG.

MA NHOLE CONSTRUCTION.

APPLICATION FILED JAN.18, 1905.

@ M-y xwa 62 d y UN TED STATES. PATENT OFFICE.

y DAV-ID CRAIG, 0F 'MELROSE, MASSACHUSETTS. mAul-cots oonsrn uorlou. I

To all whom it may concern Be it known that I, DAVID CRAIG, a citizen of the United States, and a resident of Melrose,in the county of Middlesex and State of Massachusetts, have invented new and use- Improvements in Manhole Construction, of which the following is a s ecificatiom My invention relates to t e construction of'manholes and similar openings ada ted to afford access to the interiors of tunne conduits, and'like underground chambers. Its objects'are to providea manhole-casing and the cover therefor which shall provide between them a seal against the entrance of water by means of the sinuous passage-way presently to be described; which shall also provide for ventilation when the seal is dry; the cover of which shall afford the shortest possible span between its lines of support, and consequently a maximum strengt with a minimum we' ht for a manhole of given diameter, and o tiierwise-to improve the construction of manholes and the covers therefor, as will hereinafter be pointed out.

Refe to the drawings, which illustrate one em li ifiment of my invention, Figure 1 is a plan view of the manhole-casing; and Fig. 2 is a vertical cross-section of the structure, showing the cover seated in place upon the casing.

A re resents the body of the manholecasing aving a central a erture, as shown, with substantially vertica walls. Upon the top of the casing and surrounding the central aperture are a plurality of flanges a a, forming endless channels between them. The in-' nermost of said flanges isso pro ortional with reference to the others by ma 'ng it a little longer, for instance, as to constitute a line of support or bearing for the cover. The outermost of said flanges a a is also adapted to furnish a line of support or bearing for the cover. Projecting from the lower part of the casing A is the foot or supporting-ledge a, which supports the structure and holds it in place when set in the highway over a tunnel or in other appropriate environment. The outer walls of the casing are in form flaring from the bottom toward the to as shown in the drawings, in order to rovi e a seat for the cover of suflicient brea th to accommodate the channels above described and at the same time to eliminate unnecessary Specification of Letters Patent. I 7 Application filed January 18, 1905- Berial No. 241.688-

I Patented Nov. 6, 1906.-

foot or ledge a and the outer walls of the casing proper.

B represents the manhole-covenprovided near its edge with a plurality of depending flanges b b, registeri with and rojecting into the channels of t e casing. he cover rests upon the top of the innermost and the outermost of the flanges of thecasing. It will thus be seen that the line of support or bearing between the casing and the cover bounds an area considerably smaller in span or diameter than the whole diameter of the cover, which enables a much lighter cover to be employed than when the cover is suported at its outer periphery, as has hitherto been usual. This construction and the consequent lightening of the cover affords great advantages, both in theease of manipulating the cover and in the matter of the cost of manufacture.

The flanges and channels provided uponv the cover and casing form a sinuous assa ewa which constitutes a seal upon t e princip es set forth in my Patent No. 725,937. Said flanges are preferably of tapered form in crossrsection to guard against the effects of freezing. If straight flanges are used, it is found in practice that the freezing of water contained 1n the passage-way between the flanges and its conse uent ex ansion tends to crack or break the anges. uch injurious effects are'eliminated by the use of tapered flanges, and, furthermore, the cover ma be more readily removed when pried up om one side, as is the usual practice, if tapered flanges are used than if straight flanges are use cover, I provide ventilating-apertures in 7 those flanges.

While various forms of apertures ma be employed, I prefer the notches or sea lops shown at a a. The better to insure good ventilation I provide an enlargement or pocket in the passage-wa formed between the cover and the casing elow the outer or upper end of the passage-wa as indicated at p. This is accomplished li y making the bottom of the tniterin'o'st =chan'nel of the casing-broader and deeper than the entering H e of the cover. Durst or dirt which sift in through the crevice and close the passage against ventilatio'n if the-channel fitted the flange closely will tend to fall into the pocket and keep the passage free from clogging v v The Object of the line of bearing for the cover at the outermost flange as well as the innermost flange is to prevent the possibility of any tilting o the cover and its'eonsequent tendency to slide laterally or to skate if weiig'gt should be applied to the edge.

a at I claim is 1. A manhole construction, comprising a manho'le casing a plurality-of flanges-on the upper side of the casing forming channels between them, said "flanges being so r ortioned that the innermost flange "a or' s a line of support or hearing for the cover, said supporting-flange bei provided with ventilating-a'pertures; an a cover resting 'on said supporting-flange and. provided 11' on its unde'r side with a plura'lit of depending flanges extending into the o annels of the casing.

2. A manhole construction comprising a ,man'ho'le-easing -a plurality of flanges on the ixpper side of thec'asing forming eh'annels be- 0 tween them,v said flanges bei g so proportion'ed that the innermost and outermost of said flanges aiiord lines of support or beating for the cover, said supporting-flanges being 'p'rovided'with ventilating-apertures; and a novelreeting on said supporting-flan es and provided upon its under s1de with a urality otdepending-flanges extending into tihe channels of the casing. v

3. A manhole construction comprising a manhole-casing; a pln'ralityof flanges on the upper sideof thecasing forming channels between them, said flanges being so m ortion'ed that the innermost flange -a o s a: lineof sup ort or hearing for the cover, the top of sald supportin'g-flange being notched or scalloped to afiord ventilation; and a cover restingon said supporting-flange and provided upon its under side wit a lurality of depending flanges extending into t e channels ofthe-easing Signed by me at Boston, Massachusetts, this l'lthdayof January, 1905.

DAVID CRAIG.

Witnesses:

JOSEPH T. BRENNAN,

MARGARET A. DANIHER. 

